Onshape is a fantastic option for FRC teams. Highly recommended. It’s missing CAM, though. To use your CNC “machine” (whatever kind of machine it actually is), you’ll need CAM to convert CAD models to machine instructions. Autodesk Fusion 360 is a very capable CAM option and is free to use for FRC thanks to Autodesk. Exporting from Onshape to Fusion 360 is a bit of a pain, but Onshape is so good that it’s still worth it to run that hybrid solution rather than going with only Fusion 360 for integrated CAD/CAM.
Many good points have already been made in this thread. I’m going to re-emphasize some and put a different spin on some.
I see learning CAD for FRC in multiple steps:
Learning the mechanics of using the CAD software to do CAD things. This is well covered by the free Onshape training series. I encourage all new users to go through this content. Don’t skip the training on collaboration features. Onshape makes this really seamless.
Learning how to use CAD to do FRC-relevant things with FRC-relevant materials and parts. This becomes a lot easier if you have a mentor who is already skilled with CAD for some practical use and who has also learned about building FRC robots. They can lead workshops, make videos, or provide task assistance to help students progress from CAD skills to robot CAD skills. With Onshape, the FRC-built MKCAD parts library and FRC-built Featurescripts (search CD to find these) are huge advantages in this step.
Learning to use CAD as part of the robot design process. This is making the transition from being able to efficiently CAD a robot that already exists to begin able to leverage CAD to design and manufacture a robot that has never existed. This takes time and experience. The right mentor can dramatically accelerate the process, but it’s possible to get there in more of a bootstrapping fashion over several seasons.
If you don’t have the mentor help for 2 and 3, some of the previous posts in this thread mention good public resources that can be useful for climbing the learning curve.
One of the best ways to get team members excited about CAD is how it opens up computerized manufacturing. Seeing CADed parts get made precisely on a CNC router/mill/lathe/laser/waterjet/etc. or a 3D printer is pretty motivational. Seeing those parts actually fit together and work in a mechanism is even better. Try right from the start to use CAD for practical purposes rather than as an afterthought, for “documentation”, or for just learning CAD. Even if it’s going to take a while to be designing entire robots in CAD, start out using CAD to make some critical parts. Keep working up to making mechanisms, subsystems, and eventually full robots.
It’s important to recognize that build season is not the best time to learn CAD. Learning is best done in the fall and putting the skills into practice and getting practical experience is what build season is for.
CAM has its own learning curve. Even if you have mentors who are mechanical engineers and know CAD, they may not necessarily know CAM. if they do, great, but if not, you might try to look for mentors or sponsors who are machinists or machine operators. There can be some separation between design and manufacturing in industry and you need both parts for FRC. Trade schools for advanced manufacturing can also be a good place to look for CAM help. I’ve seen fewer public training resources for CAM than for CAD, especially FRC-relevant resources. A good place to start if you are using Fusion 360 is with the videos produced by Lars Christensen.